From aeb98d0e622bab2b2d892b87cf7d84825d73327a Mon Sep 17 00:00:00 2001
From: Claude <noreply@anthropic.com>
Date: Sat, 2 May 2026 06:48:06 +0000
Subject: [PATCH] Fix false positive UselessCast for `(void)` cast on
 `#[\NoDiscard]` calls

The PHP 8.5 `(void)` cast exists specifically to discard a value and
silence `#[\NoDiscard]` warnings; it is never useless by definition.

https://github.com/phpstan/phpstan/issues/14565
---
 src/Rules/Cast/UselessCastRule.php       |  5 +++++
 tests/Rules/Cast/UselessCastRuleTest.php |  6 ++++++
 tests/Rules/Cast/data/bug-14565.php      | 18 ++++++++++++++++++
 3 files changed, 29 insertions(+)
 create mode 100644 tests/Rules/Cast/data/bug-14565.php

diff --git a/src/Rules/Cast/UselessCastRule.php b/src/Rules/Cast/UselessCastRule.php
index 66297505..4e0be959 100644
--- a/src/Rules/Cast/UselessCastRule.php
+++ b/src/Rules/Cast/UselessCastRule.php
@@ -4,6 +4,7 @@
 
 use PhpParser\Node;
 use PhpParser\Node\Expr\Cast;
+use PhpParser\Node\Expr\Cast\Void_;
 use PHPStan\Analyser\Scope;
 use PHPStan\Rules\Rule;
 use PHPStan\Rules\RuleErrorBuilder;
@@ -38,6 +39,10 @@ public function getNodeType(): string
 
 	public function processNode(Node $node, Scope $scope): array
 	{
+		if ($node instanceof Void_) {
+			return [];
+		}
+
 		$castType = $scope->getType($node);
 		if ($castType instanceof ErrorType) {
 			return [];
diff --git a/tests/Rules/Cast/UselessCastRuleTest.php b/tests/Rules/Cast/UselessCastRuleTest.php
index 2a56ca64..e0297e84 100644
--- a/tests/Rules/Cast/UselessCastRuleTest.php
+++ b/tests/Rules/Cast/UselessCastRuleTest.php
@@ -89,4 +89,10 @@ public function testReportPhpDoc(): void
 		]);
 	}
 
+	public function testBug14565(): void
+	{
+		$this->treatPhpDocTypesAsCertain = true;
+		$this->analyse([__DIR__ . '/data/bug-14565.php'], []);
+	}
+
 }
diff --git a/tests/Rules/Cast/data/bug-14565.php b/tests/Rules/Cast/data/bug-14565.php
new file mode 100644
index 00000000..bb6b0635
--- /dev/null
+++ b/tests/Rules/Cast/data/bug-14565.php
@@ -0,0 +1,18 @@
+<?php // lint >= 8.5
+
+namespace Bug14565;
+
+class Foo
+{
+
+	#[\NoDiscard]
+	public function bar(): int
+	{
+		return 1;
+	}
+
+}
+
+function (Foo $foo): void {
+	(void) $foo->bar();
+};